This is a note to let you know that I've just added the patch titled net: dsa: actually force the speed on the CPU port to the 4.2-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: net-dsa-actually-force-the-speed-on-the-cpu-port.patch and it can be found in the queue-4.2 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Wed Sep 30 05:25:07 CEST 2015 From: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx> Date: Mon, 21 Sep 2015 21:42:59 +0100 Subject: net: dsa: actually force the speed on the CPU port From: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx> [ Upstream commit 53adc9e83028d9e35b6408231ebaf62a94a16e4d ] Commit 54d792f257c6 ("net: dsa: Centralise global and port setup code into mv88e6xxx.") merged in the 4.2 merge window broke the link speed forcing for the CPU port of Marvell DSA switches. The original code was: /* MAC Forcing register: don't force link, speed, duplex * or flow control state to any particular values on physical * ports, but force the CPU port and all DSA ports to 1000 Mb/s * full duplex. */ if (dsa_is_cpu_port(ds, p) || ds->dsa_port_mask & (1 << p)) REG_WRITE(addr, 0x01, 0x003e); else REG_WRITE(addr, 0x01, 0x0003); but the new code does a read-modify-write: reg = _mv88e6xxx_reg_read(ds, REG_PORT(port), PORT_PCS_CTRL); if (dsa_is_cpu_port(ds, port) || ds->dsa_port_mask & (1 << port)) { reg |= PORT_PCS_CTRL_FORCE_LINK | PORT_PCS_CTRL_LINK_UP | PORT_PCS_CTRL_DUPLEX_FULL | PORT_PCS_CTRL_FORCE_DUPLEX; if (mv88e6xxx_6065_family(ds)) reg |= PORT_PCS_CTRL_100; else reg |= PORT_PCS_CTRL_1000; The link speed in the PCS control register is a two bit field. Forcing the link speed in this way doesn't ensure that the bit field is set to the correct value - on the hardware I have here, the speed bitfield remains set to 0x03, resulting in the speed not being forced to gigabit. We must clear both bits before forcing the link speed. Fixes: 54d792f257c6 ("net: dsa: Centralise global and port setup code into mv88e6xxx.") Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx> Acked-by: Andrew Lunn <andrew@xxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/net/dsa/mv88e6xxx.c | 1 + 1 file changed, 1 insertion(+) --- a/drivers/net/dsa/mv88e6xxx.c +++ b/drivers/net/dsa/mv88e6xxx.c @@ -1387,6 +1387,7 @@ static int mv88e6xxx_setup_port(struct d reg = _mv88e6xxx_reg_read(ds, REG_PORT(port), PORT_PCS_CTRL); if (dsa_is_cpu_port(ds, port) || ds->dsa_port_mask & (1 << port)) { + reg &= ~PORT_PCS_CTRL_UNFORCED; reg |= PORT_PCS_CTRL_FORCE_LINK | PORT_PCS_CTRL_LINK_UP | PORT_PCS_CTRL_DUPLEX_FULL | Patches currently in stable-queue which might be from rmk+kernel@xxxxxxxxxxxxxxxx are queue-4.2/net-fec-clear-receive-interrupts-before-processing-a-packet.patch queue-4.2/net-dsa-actually-force-the-speed-on-the-cpu-port.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html